Cloud heat map outputs "|" and "22" only

Just learned about the GanttProject Cloud and tried it right away because of the resource heatmap feature. So I created a test team and invited myself into it. Then I created two local test projects and added the two available resources from the cloud and some test planning.
When I now try to look at the resource heatmap, I only get the sign | and the number 22 there, where I’d expect to see the heatmap. A bug or a dumb user?

Do you have any tasks assigned to those resources in the projects stored on GP Cloud?

Like I suspected, it was about a dumb user. I had understood I could work with local projects and assign the resources from the cloud. After uploading the two test projects into the cloud and then opening those locally from the cloud, it seems to work fine!